Historically, flexible bulk containers have been used for receiving, storing, transporting and discharging flowable materials of all types. The containers are typically constructed in a square or vertically rectangular shape with lift straps attached to each of the uppermost corners of the square or rectangle.
Four panels are stitched together to form a perimeter wall which is in turn stitched to upper and lower panels to form the enclosed container. The panels used to form the perimeter wall are stitched together such that the seams connecting the panels are located in the corners of the container. The lift straps are typically stitched or otherwise attached to the uppermost corners of the container and adjacent to the seams connecting the panels to form the perimeter wall. Thus, through placement of the panel seams and the lift straps on the four corners, when filled, a substantial load is placed on the corners, thereby stressing the seam and threatening the integrity of the container.
In some instances, the ends of the lift straps are attached to the side panels at points away from the corner seams and extend up and over the corners of the top panel to form a loop. To reinforce the lift straps attached in such manner, a band of reinforced material extends vertically down the side of the container at the location of attachment of the ends of the lift straps. Thus, when the container is filled, lifting of the straps diverts some of the load stress away from the seamed corners, but concentrates more of the load on the spread apart ends of the lift straps.
The present invention overcomes the foregoing and other problems heretofore experienced in construction and use of flexible bulk containers. With reference to a first embodiment of the invention, four side panels are seamed together to form a perimeter wall which is in turn attached to a round bottom panel and, in some cases, a top round panel. Lift straps are attached to the perimeter wall of the container with the opposed ends of the straps being attached along lines beginning at adjacent seams connecting the panels and extending diagonally upwardly and away from the seams to points adjacent the attachment of the perimeter wall to the top panel. A center portion of each strap extends upwardly from the attachment points and diagonally over the top panel to form a loop above the container. Thus, the straps are attached to the container along the sides as opposed to corners of the container. Each strap is attached to its individual associated panel prior to seaming the panels to one another to simplify construction of the container. By using round bottom and or top panels to form a round container and attaching the straps to extend from the seams and loop over the containers, the load is more evenly distributed over the entire container with the added strength of a continuous piece of the container material extending around what in prior art containers would be the corner.
In a second embodiment of the invention, two side panels are attached along the bottom and both side edges to a single long panel forming the perimeter and bottom walls of a container. A round top panel is then attached to the upper edge of the perimeter wall. Thus, the construction of the top portion of the container is the same as the construction of the top portion of the first embodiment. Substitution of the single long panel for the bottom and two side panels of the container results in the container having a circular top and square or rectangular bottom. The lift straps may be attached in the same manner as in the first embodiment of the invention. As with the first embodiment, the use of a round top panel and attachment of the lift straps to extend from adjacent panel seams over the top of the container results in more even distribution of the load throughout the container, thereby reducing the threat of failure of a filled container.